U.S. Department of Defense Perchlorate Treatment Technology Workshop San Antonio, Texas. PERCHLORATE TREATMENT TECHNOLOGY Fast Track to a Solution

Transcription

1 U.S. Department of Defense Perchlorate Treatment Technology Workshop San Antonio, Texas PERCHLORATE TREATMENT TECHNOLOGY Fast Track to a Solution Richard K. (Rick) Sase, P.E. MAIN SAN GABRIEL BASIN WATERMASTER Managing groundwater for over one million people August 23, 2000

2

3 Main San Gabriel Basin Foot of San Gabriel Mountains. Low-lying mountains on south/east. Drained by San Gabriel River. 547 sq. mi. drainage area. 167 sq. mi. basin area. Basin meets 80%-90% of Valley s water demand enough for over one million people.

4 Main San Gabriel Basin designated as Superfund site due to VOC contamination Discovered in San Gabriel Valley USEPA National Priorities List Four areas named as Superfund Sites. Volatile organic compounds were/are used as industrial solvents and chemicals.

5 Discovery of Perchlorate caused shutdown of eight public drinking water wells Discovered in May wells shutdown. 2 wells being blended. 2 wells inactive due to other contaminants. and largest Superfund project stymied by discovery of perchlorate.

6 Four-pronged approach taken to fast-track development of treatment technology. SGPCT Cal Poly Formed SGPCT (10/97). Screening study by Cal Poly Pomona (6/98). Calgon M.W. Ion exchange study by Montgomery Watson (2/99). Joint-study with Calgon Carbon (10/98).

7 San Gabriel Perchlorate Coordinating Team formed to share information, pool research resources Local and regional water agencies. Regional, state and federal regulatory agencies. Potentially responsible parties. Highly-specialized technical consultants. and to fast-track peer and regulatory review process.

8 California State Polytechnic University Pomona investigated three basic treatment methods: Biological Armstrong Lab, Bioden, GAC Fluidized Bed, Autotrophic Sulfur Reactor Chemical Chemical Oxidation and Reduction, Ion Exchange Physical Nanofiltration, Reverse Osmosis, Electrodialysis, Carbon Aerogel Capacitive Deionization

9 Cal Poly conclusions on biological treatment: Pilot studies indicated perchlorate will be destroyed (no waste brine). Addition of microorganisms and potential disinfection by-products were concerns. Regulatory approval could be timeconsuming Additional studies should be conducted.

10 Cal Poly conclusions on chemical treatment: Ion exchange was most promising alternative. Calgon Carbon s ISEP treatment system resulted in low waste brine (<1%). Ion exchange technology is currently used in public drinking water systems. Waste brine disposal may become a problem in future.

11 Cal Poly conclusions on physical treatment: Reverse osmosis was proven technology and should remove perchlorate. Large volume of waste brine (10% - 30%). Disposal of waste brine was a major concern.

12 Bench/pilot scale tests by Montgomery Watson indicated feasibility of IX technology. Strong-base resin tested. Sybron Chemicals (ASB-2) Purolite (A850) Rohm & Haas (IRA 458) Perchlorate concentrations Bench/inflow: 200 ug/l Pilot/inflow: 90 ug/l Treated: ND Polystyrene resins were very difficult to regenerate. Polyacrylic (A850) resin: 725 B.V. before breakthrough, then fully regenerated.

13 Watermaster solicited engineers, contractors, suppliers and manufacturers to participate in a joint venture. Watermaster would provide site and source water. J.V. partner would provide black box treatment plant. Only one proposal was accepted: Calgon Carbon s ISEP treatment process. Photo of 25 gpm nitrate treatment plan, Campo, California.

14 Pilot-scale testing by Calgon Carbon indicated the feasibility of ISEP treatment process. Location: Big Dalton Well Baldwin Park, CA Flowrate: 4.28 gpm Brine: 0.75% of inflow Perchlorates Influent: Treated: ppb <4 ppb

15 Negotiated agreement to construct ISEP treatment plant at LPVCWD. Calgon agreed to refund costs if performance standards were not met. Construction completed in 3/00. Test period from 2/10 to 3/12/00. Reliability/ease proven in subsequent/intermittent operations. Waste brine is 0.85% of inflow.

16 Conclusions: 1. Ion exchange is a common and proven technology. used to treat public drinking water supplies. will remove perchlorate. 2. Calgon Carbon s ISEP process has additional benefits. minimizes waste brine (0.85%)/salt usage. higher safety factors due to multiple chambers. 3. Waste brine disposal may be a problem in future. 4. Partnerships, workshops and multi-prong approach resulted in a fast track to a solution.